arch/arm/rp2040: fix IN endpoint DPSRAM index for bare-eplog callers

rp2040_allocep() indexes the endpoint's DPSRAM buffer/control
registers via RP2040_DPINDEX(eplog) and RP2040_EPINDEX(eplog), both
of which take the transfer direction from the direction bit of
'eplog' itself instead of trusting the explicit 'in' argument that
is also passed to this function.

This is harmless for callers that always encode the direction bit
into 'eplog' (e.g. CDC/ACM's CDCACM_MKEPBULKIN()/MKEPINTIN(), which
OR in USB_DIR_IN), since 'in' then always agrees with that bit.  But
drivers/usbdev/usbdev_fs.c (the generic ADB/fastboot class driver)
calls DEV_ALLOCEP() with a bare endpoint number in 'eplog' (no
direction bit) and passes the direction only via the separate 'in'
parameter - matching this function's own "direction bit ignored"
contract for 'eplog' (see its Input Parameters doc, and the
pre-existing "Ignore any direction bits in the logical address"
comment, both dating back to the original driver in b860e3c4ad3).
For such a bare-number IN endpoint, USB_ISEPOUT(eplog) always
evaluates true (the IN bit is never set on a plain number), so
RP2040_DPINDEX(eplog) silently pointed the endpoint's buffer/control
registers at its OUT slot instead of its IN slot.  The real IN slot
was left unconfigured, so the SIE responded to every IN token on
that endpoint with a STALL - confirmed on real hardware via usbmon:
'C Bi:1:050:6 -32 0' (EPIPE) on every attempt, while the paired OUT
endpoint (which "accidentally" resolved to the correct slot for the
same reason) worked fine.

Fix: normalize 'eplog' to agree with the explicit 'in' argument
before it is used by RP2040_EPINDEX()/RP2040_DPINDEX(), so both
macros keep their original, single-argument form and every use of
eplog's direction bit below this point is consistent with 'in'.
Existing 0x80-encoded callers (EP0, CDC/ACM) already agree with 'in'
and are unaffected by the normalization.

Also fix two pre-existing nxstyle violations in this same file
(a misaligned comment block under USB_REQ_SYNCHFRAME, and a bare
';' body instead of empty braces on a while loop), both dating back
to the original driver in b860e3c4ad3 as well; CI runs nxstyle on
the whole file whenever it is touched.

Assisted-by: OpenCode:claude-sonnet-5
Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>